Brian: I guess I don't quite get what you are saying about the "limit of
about 150 lpi or 300 dpi"... is this something you have read somewhere, some
kind of specification? I'm sure that photopolymer probably does have a limit
as to how small a speck it can hold (ie, how fine a halftone dot), but I'm
pretty sure it is capable of holding much finer detail than most
letterpresses can print, so the limitation you speak of is not from the
plate but from the press. In any case, I cannot see how a polymer plate can
be limited by 300 dpi, since the plate is analog and the term "dpi" refers
to the digital world.

And yes, the difference between output from a 600 dpi output device and a
1200 dpi or larger resolution output device will show, but whether or not
that difference matters depends on a)what you are printing, b)what you are
printing on, c) what press you are using and d) what ink. There are probably
other factors including temperature, roller condition, what the printer has
for breakfast, and on and on... But it mainly depends on what is acceptable
quality for the printer or the client. What works for a daily newspaper
won't be considered acceptable for a slick magazine or a coffee table book
printed in Italy. One plate may look like royal doo-doo on one type of paper
and swell on another. For my own work, I tend to try to get the best
possible image from a plate, so that all the other factors which will
whittle down the quality have to start from a higher place. Having said
that, I will add there are times when a home-made neg will work and times
when it won't. Just as there are times when taking an exposed piece of film
and scratching a drawing on it will make a great negative, and times when I
need a careful rendering of an original or a computer file. I'm talking
images here. With type, I take no chances and get the best quality output
and plates I can.

Katie Harper
Ars Brevis Press
Cincinnati, OH
513-233-9588

Remember: Book arts will save the world!

> From: Brian Molanphy <bmolanphy@...>
> Reply-To: PPLetterpress@yahoogroups.com
> Date: Wed, 9 Jan 2002 20:12:22 -0700
> To: "'PPLetterpress@yahoogroups.com'" <PPLetterpress@yahoogroups.com>
> Subject: RE: [PPLetterpress] Re: another possible factor in exposing plate s
>
> katie wrote, in part:
>
> 'If you render an 85-line halftone on a 300 dpi
>> printer and compare it to an 85-line halftone rendered on a 1200 dpi
>> printer, the 1200 dpi printer output will appear sharper, crisper and with
>> better tonal rendition. If you look at both through a magnifier, you will
>> see that the dots are the same size, but the 1200 dpi dot is finer and
>> crisper.'
>>
> i get this, basically. but if polymer plates have a 'limit' of about
> 150 lpi or 300 dpi, what use is the 1200 dpi file ? the file, or the
> laserprint, may have more detail, but will that detail show up on a polymer
> plate? this question may be more meaniful if, for example, one is committing
> the heresy that i do, which is to generate negatives on my 600 dpi laser
> printer.
>
> brian
>
>
> To post a message to the membership, send an email to
> PPLetterpress@yahoogroups.com
>
> To log on to the groupsite (confirmed Yahoo ID required), go to
> http://groups.yahoogroups.com/group/PPLetterpress
> [copious reference sources can be found onsite in Bookmarks (URLs),
> Database (tables), Files (documents), and Messages (archives)]
>
> Encountering problems? send an email to
> PPLetterpress-owner@yahoogroups.com
>
> To unsubscribe, send an email to
> PPLetterpress-unsubscribe@yahoogroups.com
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>